This invention relates to outboard marine motors, and, more particularly, to an outboard motor which utilizes for cooling water obtained from the body of water in which the motor operates.
Typical outboard motors which include a four-cycle engine have an oil pan located under the engine containing the oil used to lubricate the interior of the engine. An exhaust passage used to carry fumes from the exhaust manifold, a cooling water supply passage and a waste water passage extending downward from the engine, are also located near the oil pan.
In conventional outboard motors, each of these passages is provided by separate pipes, firmly bolted to the underside of the engine near the oil pan, or to a part that acts as the engine base.
Outboard motors have a pipe open to the outside for intake of seawater, river water, or lake water which is used to cool the engine. As a result, dirt tends to accumulate in water jackets inside the engine and in cooling water passages, wastewater passages, and in other coolant passages. Over time, the flow of cooling water can be obstructed by the dirt. Thus, a flush port is provided along the cooling water passage to enable cleansing the cooling water passage with clean water. A hose from an outside clean water supply is inserted into the flush port to remove dirt from the interior of the cooling water pathway. In conventional outboard motors, the flush port is usually located inside the engine.
A problem exists in conventional outboard motors because these motors are assembled using separate pipes for the exhaust passage, the cooling water passage, and the wastewater passage. A great number of parts, such as gaskets and fasteners, are needed to maintain sealed connections between different pipes and between members making up the pipes. These conventional designs require a large number of parts, and have a complex structure, leading to an increase in assembly man hours, production costs, and weight of the outboard motor.
In outboard motors of conventional designs, the heat of exhaust gas flowing in the exhaust passage located near the oil pan heats the oil accumulated in the oil pan. This causes serious problems in the form of reduced life span and lubrication performance of the oil. In addition, the bolts that attach the pipes of the exhaust passage to the underside of the engine or to the engine base deteriorate materially because of the exhaust heat. This heating results in bending damage to the bolts.
Another problem found in conventional designs, is that when the water pressure in the cooling water pathway increases beyond what is required to cool the engine, an added load is placed on the gaskets securing the connections between components of the cooling system. This results in cooling water leaking from the connections.
Conventional designs also have a flush port used to wash the cooling water pathway with clean water. The flush port is placed on the engine itself, and requires complicated piping leading to the flush port, thus increasing the number of parts required and the number of man hours to assemble the motor. Because the entire engine is covered by an engine cover, the engine cover has to be taken off to use the flush port, increasing the complexity of flushing the engine.
Thus, there is a need for an outboard motor which overcomes the problems and limitations of the conventional art.